package net.sf.jhighlighter.ui;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.awt.Shape;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import javax.swing.SwingUtilities;
import javax.swing.event.CaretEvent;
import javax.swing.event.CaretListener;
import javax.swing.text.BadLocationException;
import javax.swing.text.Highlighter;
import javax.swing.text.JTextComponent;



/*
 *  Track the movement of the Caret by painting a background line at the
 *  current caret position.
 */
public class LineHighlighter
        implements Highlighter.HighlightPainter, CaretListener, MouseListener, MouseMotionListener {

    private JTextComponent component;
    private Color color;
    private Rectangle lastView;
    private boolean highlightingEnabled = true;

    /*
     *  The line color will be calculated automatically by attempting
     *  to make the current selection lighter by a factor of 1.2.
     *
     *  @param component  text component that requires background line painting
     */
    public LineHighlighter(JTextComponent component) {
        this(component, null);
        setLighter(new Color(255, 222, 173));
    }

    /*
     *  Manually control the line color
     *
     *  @param component  text component that requires background line painting
     *  @param color      the color of the background line
     */
    public LineHighlighter(JTextComponent component, Color color) {
        this.component = component;
        setColor(color);

        //  Add listeners so we know when to change highlighting

        component.addCaretListener(this);
        component.addMouseListener(this);
        component.addMouseMotionListener(this);

        //  Turn highlighting on by adding a dummy highlight

        try {
            component.getHighlighter().addHighlight(0, 0, this);
        } catch (BadLocationException ble) {
        }
    }

    /*
     *	You can reset the line color at any time
     *
     *  @param color  the color of the background line
     */
    public void setColor(Color color) {
        this.color = color;
    }

    /*
     *  Calculate the line color by making the selection color lighter
     *
     *  @return the color of the background line
     */
    public void setLighter(Color color) {
        int red = Math.min(255, (int) (color.getRed() * 1.2));
        int green = Math.min(255, (int) (color.getGreen() * 1.2));
        int blue = Math.min(255, (int) (color.getBlue() * 1.2));
        setColor(new Color(red, green, blue));
    }

    //  Paint the background highlight
    @Override
    public void paint(Graphics g, int p0, int p1, Shape bounds, JTextComponent c) {
        if (highlightingEnabled) {
            try {
                Rectangle r = c.modelToView(c.getCaretPosition());
                g.setColor(color);
                g.fillRect(0, r.y, c.getWidth(), r.height);

                if (lastView == null) {
                    lastView = r;
                }
            } catch (BadLocationException ble) {
                System.out.println(ble);
            }
        } else {
        }
    }

    /*
     *   Caret position has changed, remove the highlight
     */
    private void resetHighlight() {
        //  Use invokeLater to make sure updates to the Document are completed,
        //  otherwise Undo processing causes the modelToView method to loop.
        if (highlightingEnabled) {
            SwingUtilities.invokeLater(new Runnable() {

                @Override
                public void run() {
                    try {
                        int offset = component.getCaretPosition();
                        Rectangle currentView = component.modelToView(offset);

                        //  Remove the highlighting from the previously highlighted line

                        if (lastView.y != currentView.y) {
                            component.repaint(0, lastView.y, component.getWidth(), lastView.height);
                            lastView = currentView;
                        }
                    } catch (BadLocationException ble) {
                    }
                }
            });
        }
    }

    //  Implement CaretListener
    @Override
    public void caretUpdate(CaretEvent e) {
        resetHighlight();
    }

    //  Implement MouseListener
    @Override
    public void mousePressed(MouseEvent e) {
        resetHighlight();
    }

    @Override
    public void mouseClicked(MouseEvent e) {
    }

    @Override
    public void mouseEntered(MouseEvent e) {
    }

    @Override
    public void mouseExited(MouseEvent e) {
    }

    @Override
    public void mouseReleased(MouseEvent e) {
    }

    //  Implement MouseMotionListener
    @Override
    public void mouseDragged(MouseEvent e) {
        resetHighlight();
    }

    @Override
    public void mouseMoved(MouseEvent e) {
    }

    public void setHighlightingEnabled(boolean arg) {
        if (arg) {
            highlightingEnabled = true;
        } else {
            highlightingEnabled = false;
        }
    }

    public boolean getHighlightingEnabled() {
        return highlightingEnabled;
    }
}
